2D Box Plots

In Box Plots (this term was
first used by Tukey, 1970), ranges or distribution characteristics of
values of a selected variable (or variables) are plotted separately for
groups of cases defined by values of a categorical (grouping)
variable. The central tendency (e.g., median
or mean), and range or variation statistics
(e.g., quartiles, standard
errors, or standard deviations)
are computed for each group of cases, and the selected values are presented
in the selected box plot style. Outlier
data points can also be plotted (see Outliers
and extremes).